PROJECT SUMMARY/ABSTRACT The rapid increase in popularity of dual use of flavored little cigars/cigarillos (LCCs) with cigarettes among U.S. young adults has significant implications for their health, addiction, and cessation. LCCs are used for two primary reasons: their relatively lower cost and flavor offerings. As cigarettes become more expensive or less reinforcing, young adults may substitute with attractively flavored LCCs rather than quit. We do not know the addictiveness of LCCs compared with cigarettes in dual users, the role that flavors play in addiction and dual use, and if flavors are more important for women than men. Moreover, the FDA has described research on cigars and flavors as a priority. Therefore, a critical need exists to characterize the addiction potential (AP) of flavored and unflavored LCCs compared with cigarettes and differences by sex in dual users. The specific aims are to: (1) characterize the AP of LCCs compared with cigarettes; (2) determine the extent to which the AP of LCCs varies by flavor and sex of user; and (3) determine the extent to which LCC use in the home environment differs by flavored vs. unflavored. The proposed study will employ a 3-week crossover design that combines survey-based measures (including behavioral economic assessments), biomarkers, and ecological momentary assessments (EMAs) of AP, dependence, and tobacco use behaviors among 145 non-treatment-seeking young adult (18-34 years old) dual users. AP will be characterized by behavioral economic indices of demand, such as the hypothetical consumption of LCCs at escalating prices, and other standardized measures of addiction. The impact of flavors on LCC and cigarette smoking at home will be captured by EMA. This information will address the following FDA priorities: impact of changes in LCC flavors on dependence and dual use behaviors, and innovative methods to assess tobacco use behaviors. The career development plan combines mentored hands-on training with coursework and professional development activities to meet the objectives critical to my transition to independent tobacco regulatory scientist. My career goal is to conduct research that develops our understanding of tobacco use in vulnerable populations, and informs tobacco regulation to reduce disease. I propose additional training in addictions research (including clinical trials), measurement of dependence and addiction potential, cigar regulatory research, and grantsmanship. With this training and my prior experience, I will be able to transition to an independent investigator of tobacco product flavorings and other characteristics that?with cognitive, affective, behavioral, and environmental influences?contribute to their uptake, use, and addiction. UConn Health, Brown, and Rutgers provide excellent resources for my career development, including formal coursework, seminars, expert faculty, research centers, office space, equipment, software, and data collection, analysis, and management resources. The focused training provided by this Award represents the final step in my career development and provides preliminary data and training for planned R-level grant writing.